Observations on the energy budget were carried out from the middle of January to the middle of February, 1994, at Cambridge Bay, Northwest Territories, Canada. And using upper air data, which was obtained by A.E.S.(Atmospheric Environment Service), the heat budget analysis was also done. Furthermore, BASE (Beaufort and Arctic Storms Experiment) was conducted near the region of Beaufort Sea from the beginning of September to the middle of October, 1994. This experiment was included of the aircraft, radar and satellite observations. We set our dual polarization Doppler radar at Tuktoyaktuk, which is faced on Beaufort Sea, and observed Arctic storms during the BASE period.1.Some automated observations had been carried out at Cambridge Bay and Resolute N.W.T., Canada about vertical gradient of surface air temperature and air temperature from September 1992 to April 1993. In addition of them, air temperature and wind speed at the height of 20m, 40m and 66m had been measured at Cambridge Bay
… More from September 1993 to April 1994. According to the observational results, negative gradients of air temperature are noted to take place due to the surface inversion caused by radiative cooling and due to apparent surface inversion caused warm advection after cold advection. Since the former and latter cases are considered to correspond to source and sink of cold air, respectively, in comparison between two observational points, it is marked that the occurrences probabilities of the former to latter cases were greater at Cambridge Bay. than that at Resolute.2.We observed wind and air temperature near the ground at Aerological station in Cambridge-Bay, North-west Territories, Canada (69.3 N,105.0 W) to make clear the characteristics of fluctuations of them and momentum and heat transports between atmosphere and the surface of the earth when cold air formed in Canadian Arctic in winter. We measured horizontal and vertical wind velocities and air temperature by ultra sonic anemometer (WAT-395) and recorded them by digital recorder (DR-F1) with 1 to 10 Hz sampling time. We cleared the characteristics of fluctuations of wind speed and air temperature using spectrum and wavelet analysis and momentum and heat transports using eddy correlation method.3.From 16 January to 7 February in 1994 snow crystals and ice crystals were observed at Cambridge Bay in Canada. Most of observed snow crystals had beautiful shapes and were inferred to fall through very cold saturated space after grown in thin stratus cloud. Hexagonal single crystal plates were found to grow in considerable high frequencies at temperatures below -25ﾟC and growth conditions of snow crystals of a few low temperature types were analyzed. Ice crystals formed in ice fog were also observed and it was found that ice fog can be divided into two types by the deference of crystal shapes.4.The Yamase circulation is a very cold NE-ly wind observed in the northern Japan in the summertime, and is directly driven by the pressure gradient between the Okhotsk High and the low pressure zone to the south of Japanese Islands. Generation mechanism of the Yamase circulation has been studied by analyzing objectively analyzed data of the upper air observations (NMC) and the gridded data of sea-ice concentrations over the Arctic ocean (NASA). The cold air mass brought by the Yamase circulation has been found to come from the Arctic ocean through the Bering Strait.ヤマセは夏季に北西太平洋から北日本に吹き込む冷たい北東気流であり、オホーツク海高気圧と日本列島南方の低圧帯の気圧差によって駆動されている。ヤマセの発生機構について、高層気象の客観解析データ、北極圏の海氷分布データなどを解析して詳細に調べた。ヤマセの寒気の源は、北極海からベーリング海峡を通って太平洋へ流れ出る北極気団であることが明らかになった。地表でヤマセが吹くとき、500hPa面高度では偏西風が波数3の循環を示し、オホーツク海周辺の極東域では偏西風の分流・ブロッキングが発生している。ヤマセの原因である3波数循環と偏西風の分流・ブロッキングは、極気団の中心がバレンツ海周辺にあり、バレンツ海周辺の海氷例年より広く分布している場合に発生していることが判明した。また、大冷害をもたらす持続性の強いヤマセは、偏西風がヨーロッパ周辺から二本の流れ(亜熱帯ジェット、亜寒帯ジェット)に分かれ、その間に持続性の短いブロッキングが次々に生じることによって維持されていることが明らかとなった。 Less